Liverpool squad depth concern as Klopp fails to keep up with Chelsea

For all the talk of slumps and being unable to beat the lesser teams, it's often overlooked that when Liverpool have had their first choice players (specifically the front six) on the pitch this season, more often than not they have been very impressive.

They won at Arsenal and Chelsea and only an assistant referee's errant flag robbed them of a win at Tottenham. They put that right by beating the Londoners at Anfield last weekend, and all of those fine results and performances -- as well as plenty of others -- came with Klopp's preferred midfield and strikers on the field.

When one or more has been missing, however, it's been a different story. Sadio Mane was absent when the Reds lost at Burnley in week two of the season, and everyone saw what happened when the Senegal man missed the entire month of January due to his participation in the African Nations Cup.

While Mane is undoubtedly a fine player, he's not Luis Suarez and in theory Liverpool should have been able to cope without him. That they can't is simply down to how unbalanced the squad is currently.

Neither Daniel Sturridge nor Divock Origi have been able to adequately fill in when Mane or Philippe Coutinho has been unavailable, and the drop off in quality when Emre Can has replaced either Lallana or Georginio Wijnaldum in midfield has been glaring.

Liverpool's best performances usually come when they play at a high tempo, ferociously press the opposition and move the ball quickly. Can isn't adept at any of that and often slows things down by taking too many touches. He is a good player but his style often appears to be completely at odds with how Liverpool like to play. The same can be said of Sturridge and (to a slightly lesser extent) Origi for that matter.

Hindsight is 20-20 of course and going into the season one of Liverpool's main strengths looked to be the depth they had in attacking areas. Few teams can boast players of the calibre of Sturridge and Origi on their bench, but what initially looked like a strength has surprisingly proved to be a weakness.

The midfield hasn't functioned as well with Can in it and the forward line has looked unbalanced when either or both of Sturridge and Origi have played.

This is the main thing Klopp needs to address this summer. He has to add several players to his squad who can fit in seamlessly with how the first XI plays. He can achieve that by either upgrading on his first choice midfield and forwards (which is not easy) or by bringing in players who possess similar attributes to his starters.

Liverpool's top priority should be identifying and signing another Mane type player, while they could also use an alternative to Coutinho. If Leicester are relegated, then perhaps Riyad Mahrez might be an option?

Another box-to-box midfielder is also required (how Liverpool could have done with Joe Allen this season) as well as competition/cover for Jordan Henderson in the holding role. If Can remains at the club -- and the current impasse in contract talks puts that in doubt -- then he should only be considered for the role Henderson occupies, as he is incapable of replacing Lallana or Wijnaldum.

Sadio Mane has inspired Liverpool this season but the Reds have slipped up in other areas.

Klopp felt his squad was strong enough going into the season but sadly that hasn't proved to be the case. This is the main reason why Liverpool couldn't keep pace with Chelsea and also why they were eliminated from two cup competitions in the space of four days.

Worryingly, Liverpool's lack of depth has been exposed in a season in which they have not had to deal with the demands of European football. Even with one game a week there have been problems with fatigue and injuries, so if they secure a place in next season's Champions League, just how many players will Liverpool need to sign to be able to cope with it?

The Europa League would also be problematic, but at least in that competition there's the option of fielding a second string in the group stages. Supporters almost expect that these days and few would be too critical of Klopp if he sent "the kids" to an away fixture in Latvia or Moldova, for example.

The Champions League is different, though, as Brendan Rodgers discovered when he rested players against Real Madrid ahead of a crucial league game with Chelsea just a few days later. There wasn't just a fan backlash after that, even his own players were angry, as Steven Gerrard would later reveal that being left out of that game was the moment that made him decide to leave Anfield.

Champions League qualification would certainly bring problems but it would also make Liverpool more attractive to their transfer targets and provide them with significant extra funds to improve the squad. Should they secure a top four spot this year, Liverpool simply must use both of those things to their advantage in the summer.

Klopp's first XI is very good so that's half the battle won. Now he just needs to bring in genuine competition for those players if Liverpool are to make that next step.

Dave Usher is one of ESPN's Liverpool bloggers and the founder of LFC fanzine and website The Liverpool Way. Follow him on Twitter: @theliverpoolway.